Windows 10 Will Be A Free Upgrade If You Have Windows 7 Or 8

Terry Myerson, Microsoft's executive vice president of operating systems. Business Insider Microsoft announced Wednesday that its new version of Windows, Windows 10, will be a free upgrade for Windows 7 and 8.1 users.

It should also help quickly drive adoption for the new operating system. Windows 7 is the most popular version of Windows, even though it's several years old. Users have been hesitant to upgrade to Windows 8.1 since it has a radically different interface.

Windows Phone 8.1 users will also be able to upgrade to Windows 10 for free. Windows 10 is designed to work on all Microsoft gadgets: phones, PCs, tablets, and even the Xbox.

Windows 10 takes a step back from Windows 8.1 and includes an interface that's easier to use on traditional desktops and laptops. It can also adapt to different form factors. So, for example, if you're using a hybrid tablet/laptop device, the interface will change depending on which way you use it.

The free upgrade offer is only good for the first year after Windows 10's debut. Microsoft hasn't announced a launch date yet, but it'll arrive before the end of 2015.